The present invention broadly relates to a new and improved device or apparatus for manipulating workpieces in a machine, such as a press and, more specifically, pertains to a new and improved construction of a device or apparatus for manipulating workpieces, especially sheets or panels in and around the operating region of a die of a bending press.
A device for manipulating workpieces in a press area of a forging press is known from the German Patent Publication No. 2,806,987, granted Aug. 21, 1980. The upper of two superimposed transport carriages for motion in a forward and backward direction or for to-and-fro movement carries a lifting carriage on a vertical spindle. The lifting carriage comprises a jaw carriage having at least one manipulating jaw and at least one adjusting gear rack driven by a pinion mounted on the vertical spindle. The manipulating jaws are actuated by an actuating cylinder and piston mechanism. This device is suited for individual processing of workpieces, such as forging, drop forging or punching. The disadvantage of this device is that the manipulating jaws release the workpiece for operations in the press and remain outside of the operating region of the press during the work stroke. The jaws must reengage the workpiece for each subsequent manipulation required for further processing.
German Patent Publication No. 2,847,543, published Aug. 21, 1980, discloses a loading and unloading device for presses or similar machine tools whose function is to lift a workpiece from a pile or stacking area, to deposit it in the operating region of a press or a punch and to lift it out of the die again after completion of the operation and to deposit it on a pile or stacking area. To achieve a predetermined sequence of motion comprising essentially straight line horizontal back-and-forth motions with vertical motions in both end phases, a portion of a four-bar or parallelogram linkage is employed as a transport arm driven by a corresponding cam plate and crosshead or crank rocker mechanism. This device is also suited for delivering material to presses or punches in which the workpiece is processed while the loading device remains outside of the operating region of the press. The disadvantage of this known device is that it, too, releases and regrips the workpiece for each operation or for unloading it.